Bobbin



July 7, 1953 w. F. 'STAHL Em; 2,6441351*4 BoBBIN A Filed May 3, 41950 IN ENTORS.'

ATTORNEYS.

Patentecl July 7, 19.53

UNITEDv STA-rss PATENT I william F. stam, Kenilworth, and Fred v. collins, DesPlaines, Ill.; said Collins assignor to `said stahl This invention relates to bobbins and to a process for making them; in particular, it concernsan improved bobbin or coil form of the type com-- monly employed in .industry for holding trans- AppiicationMay's,195o,seria1No.159,756 Q 1 7 claims. (01.242-119) 'v l 2 l Y .l It is accordingly a major object of our to provide a method of making coil forms where'- in terminal flanges are anchoredinfplacerfby' chemical-mechanical means, without'Y fswaging,

former windings and the like, and to a method and without the use of centering: sleeves or any' of making such bobbins or coil forms. i equivalents thereof. "11 ;.1 Coil forms or bobbins of the type here under Another object of our invention .is to provide. consideration have avery extensive use inthe a coil form or bobbin which, whilepossessing: electrical industry, millions of them Ybeingl used great mechanical strength and rigidity,` 'can be annually in the United States as supports for 1.0 assembled, and .its terminal langes locked in4 electrical windings. Such a form or bobbin conplace, in a single mass operation, hundreds or' sists, in general, of a core-which -may be circuthousands of forms being simultaneously proc-f lar, square, or rectangular in crossy section-l-proessed. f Y y vided at its respective ends with terminal anges Still another object of our invention is to prowhich extend radially outward at right angles to l5 vide a bobbin or coil form comprising a plastic-v the axis of the core. In vthe most commonly used coated laminated core equipped ywith terminal form, the core is made of laminated paper and ilanges chemically locked in place byswellingfthe the terminal anges are .formed of hard ber. plastic. core after the anges are lfsnugly fitted In the prior art, so far as We are aware, such thereover. f I coil forms have been universally made by placing A still further object of our invention is to profthe flanges on the ends of the core and then swagvide a novel chemical bath in which bobbins or`v ing the core ends to lock the anges in place. In coil forms made according toour method can be many cases, to prevent the swaging actionfrom treated en masse to anchor the terminal anges forcing the flanges too far inward along the core, to the core by chemical action, Without necessity the core has been provided with a central zonelof Z5 for swaging, z larger dimensions than its terminal zones, as by Other objects and advantages of our invention covering the laminated paper core with an addiwill appear as the specification proceeds.`. tional sleeve of-paper or ber. This central 4zone The appended drawing shows an illustrative of increased dimension would, during the swafging embodiment of our novel coil form, made accord. operation, serve as an anchor for the anges and, ing to the process of our invention. In thedrawafter swaging, the flanges would be securely ing, Figure 1 is a perspective view of acoil form' locked between the outer ends of the increasedor bobbin embodying our invention; Fig.- 2, a side; dimension zone and the swaged extremities of View in cross section of the coil form of Figli as thecore proper. it appears prior to assembly, with. the core and The mode of manufacture -J`ust described has terminal iiangesl shown separately; AFig.,3, a sec been in universal use for a number of years and tional view similar to Fig. 2 but showing the ap;- has been highly satisfactoryso raras the perpearance of our coil form afterthe terminali formance of the end product is concerned. It is anges have been placed in correct position-fon a relatively expensive manufacturing technique, the core and anchored therein by being subjected however, for the reason that each individual form to treatment in a chemical bath; and Fig. 4, a or bobbin must be subjected to vmechanica1 swaggreatly enlarged fragmentary view of a portion ofV ing-an operation Which calls for expensive ma Fig. 3, Showing in detail the mannerin which the Ychinery and which consumes considerable time. terminal ange iS Secured t0 the COIB after Chemi- We have, in the present invention, provided a Cal processing. j means of making bobbins or coil forms of the type In' carrying out the process of our invention,` just described which produces an end product we provide laminated paper cores, which may fully as satisfactory as the bobbins made by the be conventional, with a thin layer of plastic, prefswaging technique and at a muchreduced manuerably cellulose acetate, wound over the surface facturing cost. Bobbins viliade by ourV process of the core to form a continueus'sngle layer have very great mechanical strength, are conthereon.' Such winding can easily -be done fin'thef; sistently uniform in dimensions, and can be proccourse of manufacturing the cores; Onthe' i essedin batches of several hundreds or thousands drawing, the core of the coilform ythereinv illusat one time, in contrast to the swaging, ofthe trated is denoted il and 'the plastic -laye "deprior art which must be performed individually posited thereon is denoted l2. .fp on each bobbin. i 55 'I'he terminal flanges, which rmay, be conveninvention- In the case of the particular embodiment shown, providing flanges I3 and I4 with the in-f dentations I5 permits the construction of a coill v Vm"for use.

.-'zobtained-withfthissbath when the coil forms lWere form in which the outer perpendicular surfaces of flanges I3 and I4 are flushwi'thltherespective1*# ends of core II, there beingnevertheless'l-asmall* zone II of core I I projecting beyond the apertures I6, as may be best seen in Figs. 3 ander.;

Flanges I3 and I4 are placed over the coilform is finished. rThis may be done mechanically or byfhand, according `to the magnitude of the :manufacturing operation.. l The coil lform, alonggwith as many hundreds or thousands of' 'core-Iii the position which it is desired they occupyl'fwhen similar-:coil forms `as the sizeof thefacilitiesfwill;

permit, is then placedina lchemical bath operai'.

tive to soften and swell the plastic layer? t2.- HEX;- posure to the bath for-an interval: from oneto nve secondsresultsin substantial swelling of `all the, y

plastic 'layer I2 which is able to contact thel bath.

As a result, ythe-,plastic :layer promptly swells,l asV indioatedinzl'igs and 4, and securely locksthe fianges'I3 and I4 into proper position oncore I I.A

After the forms have been removed fromt-hebath, they are driedpreferablyby exposure to controlled heat inan oven-and'arewthen ready r for shipment or use. 1

-We .have found .that the? mechanical Ystrength of coil forms made according to. our invention is:

fully equal to, and in some cases exceeds, -the mechanicalV strength of similar coilforms `made according lto the prior-'art swagingy method.

The chemical composition vof the treating-'..bath `may'take any 'desired form within wide limits.. In general, the treating bath should comprise a..y

moderate amount of a swelling agent combined with substantiallygreater quantities .ofI solvent.

While widediscretionin the choice of solvents land their proportions .may be allowed, the composition employed will greatly influence the length of time7 required 'for the bath to effect the swelling-'fand settingactions whichA in our invention' accomplish the anchoring ofthe flangesto the core. l We 'havev found that effective yet extremely. rapidi results" can vbe obtained-When the swelling agent is combined with va'plurality of solvents having'radically different time characteristics. 'In our-most satis-5l factory compositionswe have employed a rela-- tivelysmall quantity of a mild solvent combined with larger and substantially equal quantities of j an active solvent and an extremely `active solvent.

The swelling 'agent,-when celluloseacet'ate is' employedas theplastic coating on the 'cor'e,j .may`r be lselected from among the' ketone's'; Vvr'ehave'v found methyl isobutyl ketone.particularly'satisfactory. ,v

AVl/hileit is not necessary in withstand mechanical abuse. We'ihavei foundzdi# butyl lphthalate and' tri (2fchloroethyl'):phosphateI satisfactory plasticizers. for.;thispurpose -Following aretwo :examplesiof :bathrcompositions found to be highly successful in practicing the method of our invention:

E @ample I A bath was made up of 601 parts of tetrahydrofuran, an extremely active solvent for cellulose acetate, 50 parts of acetone, a somewhat less active s olventgjg'and 2O parts' of`= ethylene glycol monomethylietherfa mildfsoftening solvent, and 10 parts of methyl isobutyl ketone, the swelling agent. The ingredients were mixed thoroughly ,at room temperature, and the bath was then ready It was found that excellent results were :placed:nit'lforiaaperiod of ve seconds.

'ample II A bath'for carrying out our invention 'Was'prepared by employing 64 parts of furfural,

40 parts of ethylene glycol monomethyl ether, and LIO-'parts-'of methyl 'isobutylketone These ingredients were fmixed=thoroughly `at room" temperature. and tdtheml was added one part yof dibutyl phthalate. 'Y The resulting bath fwas' .employedlat room Ytemperature inlthe practice 'of our invention. It was found that immersion ofthe c'o'ilforms'in :the bath for intervals of `one'to 'five seconds effectively swelled the plastic coatings on thercores andprovided excellent anchorage for the terminal-flanges. v

.It 'willbe understood, of course, that the construction-.shown in the drawing, which employs theaxial indentations; I 5 inthe terminal flanges, is lmerely a preferred form. If the application doesnot require thatthe surface 'of the flanges be ushfwiththe ends ofthe core, planar terminal anges maybe employed.

While wehave 'in this specification `'described in"detail particularembodiment of our invention; and .certain particular .techniques for `practicingourprocess, it will be understood that these are forfillust'ration only. Many variations, both m' the''productfandthe process, 'will occur to persons `'skilled in 'the vart without Jde'parti'nglfrom the-spirit'of -our invention. v

We claimrf1.' VA rbobbin' comprising a core having a Y thin outer layerfof lplastic adapted `to swelll upon' application' ofv appropriate yswelling agents, and

alflange'tted-snugly over said core and plastic intermediate the'ends of said core, said 'flange being-:anchored to said core byswollen zones of enlargedthickness of said-'plastic on both sides of said flange. l

2. A'bobb'incompidsingl a core having a thin outerll'ayer of 'plastic vextending fromerid to end thereofand adaptedvto swellwhen subjected to theaction of suitable Iswelling agents, Vandl a pair of 'terminal flanges'flttedsnugly Vover said layer 1^ and@ core intermediate'ithe'ends thereof, said flan'geslbeing anchored' to .saidcore by swollen zonesf'o'ffenlarged thicknessY of v'said-plastic onA outer layerio'fcellulose `acetateand a flange fitted snuglyf. over said llayeran'dcorev intermediate the ends thereof; said flangefbeing anchored to saidy core hby .swollen-I 'zones fof enlarged thickness Aof said-:acetate substantially-abutting Isaid flange plastiblayer toaextendilonibothi-sidesof the central aperture when the principal portion offtheY 5 flange is substantially ilush with the end of the core.

5. A bobbin according to claim 2 wherein said core is of uniform cross section throughout its length, and the flanges are provided with central apertures and with symmetrical axial deformations operative to permit the plastic layer to extend on both sides of both flanges when the principal portions of the respective flanges are oriented substantially flush with the respective ends of the core.

6. A bobbin, comprising a core having a uniform cross section throughout the length thereof, said core having a thin outer layer of a normally hard material adapted to swell upon the application of suitable swelling agents, at least one flange snugly received about said core intermediate the ends thereof, each of said anges being rmly anchored to said core by swollen Zones of said material providing enlargements substantially abutting each flange on both sides thereof.

7 A bobbin, comprising a core having an outer surface composed of a normally hard material adapted to swell in response to the action of suitable swelling agents, at least one flange snugly received about said core intermediate the ends thereof, each flange being firmly anchored to.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 948,430 Omeliah Feb. 8, 1910 1,731,219 Atwood Oct. 8, 1929 2,027,962 Currie Jan. 14, 1936 2,183,691 Owens Dec. 19, 1939 2,228,108 Bjorksten Jan. '7, 1941 2,254,109 Bjorksten Sept. 2, 1941 2,294,711 Bjorksten Sept. 1, 1942 2,299,113 Seever Oct. 20, 1942 2,314,749 Willner Mar. 23, 1943 2,375,704 Stahl May 8, 1945 2,519,340 Lenox Aug. 22, 1950 

